Project Summary The goal of this proposal is to characterize biomarkers of marijuana smoke exposure in ART-treated HIV+ adults over age 40, and their relationship to inflammation and vascular injury in heavy users. Marijuana and tobacco smoking are both prevalent among HIV+ populations, but their individual and combined impacts on inflammation and cardiovascular risk are unknown. Preliminary studies using longitudinal data from a prospective cohort showed that chronic heavy marijuana smoking has no significant effect on HIV disease markers, but is associated with increased rates of incident cardiovascular events in ART-treated HIV+ men age 40-60 independently of tobacco smoking and traditional risk factors. Furthermore, we showed that heavy marijuana and/or tobacco smoking was associated with elevated WBC and neutrophil counts, immune activation, inflammation, and vascular injury in ART-treated HIV+ smokers. We hypothesize that specific combustion products in marijuana and tobacco smoke, including acrolein, other reactive aldehydes, and VOCs, can induce proinflammatory responses mediated through activated neutrophils and monocytes that promote chronic inflammation in ART-treated adults, contributing to cardiovascular risk by promoting lipid peroxidation, coagulation, vascular inflammation, and endothelial injury, while attenuating protective responses. We further hypothesize that these effects are additive upon dual exposure to both marijuana and tobacco smoke and augmented by HIV infection. To address these questions, we will use clinical samples and data from well- characterized longitudinal HIV+ cohorts to characterize marijuana smoke exposure biomarkers in plasma and urine samples and their relationship to inflammation, oxidative stress, and vascular injury. Bioinformatics, computational modeling, and cell culture models will be used to build and test models to explain the effects of specific constituents of marijuana smoke on inflammatory pathways, and how these pathways are modified in the setting of HIV infection. These studies will provide information that helps to explain chronic inflammation and elevated cardiovascular risk in ART-treated HIV+ adults, safety profiles of smoked cannabinoids, and potential strategies for therapeutic intervention.